Mitigation of calibration errors

ABSTRACT

Wireless communications systems and methods related to mitigation of calibration errors are provided. A base station (BS) transmits, via an antenna array including a plurality of antenna elements, a first communication signal using a first number of the plurality of antenna elements and a first transmission power level to a user equipment (UE). The BS receives from at least one UE, a measurement report based on the first communication signal. The BS transmitting a second communication signal using a second number of the plurality of antenna elements and a second transmission power level based on the one or more measurement reports. At least one of the first number of the plurality of antenna elements is different from the second number of the plurality of antenna elements, or the first transmission power level is different from the second transmission power level. Other aspects and features are also claimed and described.

TECHNICAL FIELD

This application relates to wireless communication systems, and moreparticularly to improving transmission performance by mitigatingcalibration errors at a base station. Embodiments enable and providesolutions and techniques for improving calibration accuracy.

INTRODUCTION

A wireless communication network may include a number of base stations(BSs) that can support communication for a number of user equipments(UEs). In Long Term Evolution (LTE), BSs are referred to as evolvedNodeBs (eNBs). In recent years, the carrier frequencies at which BSs andUEs communicate have continued to increase and include largerbandwidths. To take advantage of these higher frequencies, more antennasin the same physical aperture have been used. For these higher frequencybands to be useful and approximate the same coverage radius as priortechnologies (such as 2G, 3G, or 4G), however, more beam forming gain(and more accurate) beamformed transmissions are becoming necessary.

Reciprocity describes the ability for a wireless device to useinformation (such as angles-of-arrival and delays) from one channel(e.g., the DL) in making determinations regarding another channel (e.g.,the UL). In time-division duplexing (TDD) systems, after circuitmismatches have been compensated, the physical UL channel and thephysical DL channel are identical (or transpositions of each other froma matrix algebra perspective) since UL and DL operate in the samefrequency band. For example, BSs may compute UL channel estimates basedon UL reference signals such as sounding reference signals (SRSs)transmitted by UEs and use the UL channel estimates for DL beamforming.In another example, the UE may compute DL channel estimates based onsecondary synchronization block (SSB) or channel stateinformation—reference signals (CSI-RS) transmissions transmitted fromthe BS and use this information for UL channel estimates in ULtransmissions. However, in practice, a communication channel between apair of nodes (e.g., a BS and a UE) includes not only the physicalchannel, but also radio frequency (RF) transceiver chains, for example,including antennas, low-noise amplifiers (LNAs), mixers, RF filters, andanalog-to-digital (A/D) converters or digital-to-analog (D/A)converters, and in-phase quadrature-phase (I/Q) imbalances, which may bedifferent between different nodes and/or different antennas. Thus, eachnode can introduce a mismatch, for example, in amplitude and/or phase,to transmitted and/or received signals. The mismatch may impactperformance of channel reciprocity-based transmissions.

BRIEF SUMMARY OF SOME EXAMPLES

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

Embodiments of the present disclosure provide mechanisms for mitigationcalibration errors. Implementations can occur from both networkperspectives (e.g., at the base station (BS)-side) or non-networkperspectives (e.g., UEs, relays, nodes, etc.). Calibration is theprocedure by which phase and amplitude at every antenna are ensured toreplicate the desired response with a certain excitation. Withoutcalibration, receive beam weights may not produce the correct behavioras intended. Calibration helps correct the phase and amplitudemismatches between transmit and receive circuitry (e.g., due tomismatches in amplifiers, mixers, filters, couplers, etc.). Transmit andreceive beam weights are typically assumed to be reciprocal.Accordingly, without calibration, the receive beam weights may not bereused for the transmission. Mitigation of phase and amplitudecalibration errors may involve modifying the array size, transmissionpower levels, and/or a beam codebook at the BS-side.

For example, in an aspect of the disclosure, a method of wirelesscommunication includes transmitting, by a base station via an antennaarray including a plurality of antenna elements, a first communicationsignal using a first number of the plurality of antenna elements and afirst transmission power level; receiving, by the base station from atleast one user equipment, a measurement report based on the firstcommunication signal; and transmitting, by the base station, a secondcommunication signal using a second number of the plurality of antennaelements and a second transmission power level based on the measurementreport, where the at least one of the first number of the plurality ofantenna elements is different from the second number of the plurality ofantenna elements or the first transmission power level is different fromthe second transmission power level.

In an additional aspect of the disclosure, an apparatus includes atransceiver configured to transmit, by a base station via an antennaarray including a plurality of antenna elements, a first communicationsignal using a first number of the plurality of antenna elements and afirst transmission power level; receive, by the base station from atleast one user equipment, a measurement report based on the firstcommunication signal; and transmit, by the base station, a secondcommunication signal using a second number of the plurality of antennaelements and a second transmission power level based on the measurementreport, where the at least one of the first number of the plurality ofantenna elements is different from the second number of the plurality ofantenna elements or the first transmission power level is different fromthe second transmission power level.

In an additional aspect of the disclosure, a computer-readable mediumhaving program code recorded thereon, the program code includes code fortransmitting via an antenna array including a plurality of antennaelements, a first communication signal using a first number of theplurality of antenna elements and a first transmission power level; codefor receiving from at least one user equipment, a measurement reportbased on the first communication signal; and code for transmitting asecond communication signal using a second number of the plurality ofantenna elements and a second transmission power level based on themeasurement report, where the at least one of the first number of theplurality of antenna elements is different from the second number of theplurality of antenna elements or the first transmission power level isdifferent from the second transmission power level.

In an additional aspect of the disclosure, an apparatus includes meansfor transmitting a first communication signal using a first number of aplurality of antenna elements and a first transmission power level;means for receiving, from at least one user equipment, a measurementreport based on the first communication signal; and means fortransmitting a second communication signal using a second number of theplurality of antenna elements and a second transmission power levelbased on the measurement report, where the at least one of the firstnumber of the plurality of antenna elements is different from the secondnumber of the plurality of antenna elements or the first transmissionpower level is different from the second transmission power level.

In some examples, in an aspect of the disclosure, a method of wirelesscommunication includes receiving, by a user equipment from a basestation, a first communication signal; transmitting, by the userequipment to the base station, a request to change at least one of anantenna array size at the base station or a transmit power level at thebase station based on the first communication signal; and receiving, bythe user equipment from the base station, a second communication signalin response to the request.

In an additional aspect of the disclosure, an apparatus includes atransceiver configured to receive, by a user equipment from a basestation, a first communication signal; transmit, by the user equipmentto the base station, a request to change at least one of an antennaarray size at the base station or a transmit power level at the basestation based on the first communication signal; and receive, by theuser equipment from the base station, a second communication signal inresponse to the request.

In an additional aspect of the disclosure, a computer-readable mediumhaving program code recorded thereon, the program code includes code forreceiving, by a user equipment from a base station, a firstcommunication signal; code for transmitting, by the user equipment tothe base station, a request to change at least one of an antenna arraysize at the base station or a transmit power level at the base stationbased on the first communication signal; and code for receiving, by theuser equipment from the base station, a second communication signal inresponse to the request.

In an additional aspect of the disclosure, an apparatus includes meansfor receiving, from a base station, a first communication signal; meansfor transmitting, by the user equipment to the base station, a requestto change at least one of an antenna array size at the base station or atransmit power level at the base station based on the firstcommunication signal; and means for receiving, from the base station, asecond communication signal in response to the request.

Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments inconjunction with the accompanying figures. While features may bediscussed relative to certain embodiments and figures below, allembodiments can include one or more of the advantageous featuresdiscussed herein. In other words, while one or more embodiments may bediscussed as having certain advantageous features, one or more of suchfeatures may also be used in accordance with the various embodimentsdiscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments it should beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network according to someembodiments of the present disclosure.

FIG. 2 illustrates a communication method according to some embodimentsof the present disclosure.

FIG. 3 illustrates a communication method according to some embodimentsof the present disclosure.

FIG. 4 is a block diagram of an exemplary base station (BS) according toembodiments of the present disclosure.

FIG. 5 is a block diagram of an exemplary user equipment (UE) accordingto embodiments of the present disclosure.

FIG. 6 illustrates a signaling diagram of a method for mitigatingcalibration errors according to some embodiments of the presentdisclosure.

FIG. 7 is a flow diagram of a communication method according toembodiments of the present disclosure.

FIG. 8 is a flow diagram of a communication method according toembodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

This disclosure relates generally to providing or participating inauthorized shared access between two or more wireless communicationssystems, also referred to as wireless communications networks. Invarious embodiments, the techniques and apparatus may be used forwireless communication networks such as code division multiple access(CDMA) networks, time division multiple access (TDMA) networks,frequency division multiple access (FDMA) networks, orthogonal FDMA(OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks,GSM networks, 5^(th) Generation (5G) or new radio (NR) networks, as wellas other communications networks. As described herein, the terms“networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA(E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and thelike. UTRA, E-UTRA, and Global System for Mobile Communications (GSM)are part of universal mobile telecommunication system (UMTS). Inparticular, long term evolution (LTE) is a release of UMTS that usesE-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documentsprovided from an organization named “3rd Generation Partnership Project”(3GPP), and cdma2000 is described in documents from an organizationnamed “3rd Generation Partnership Project 2” (3GPP2). These variousradio technologies and standards are known or are being developed. Forexample, the 3rd Generation Partnership Project (3GPP) is acollaboration between groups of telecommunications associations thataims to define a globally applicable third generation (3G) mobile phonespecification. 3GPP long term evolution (LTE) is a 3GPP project whichwas aimed at improving the universal mobile telecommunications system(UMTS) mobile phone standard. The 3GPP may define specifications for thenext generation of mobile networks, mobile systems, and mobile devices.The present disclosure is concerned with the evolution of wirelesstechnologies from LTE, 4G, 5G, NR, and beyond with shared access towireless spectrum between networks using a collection of new anddifferent radio access technologies or radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diversespectrum, and diverse services and devices that may be implemented usingan OFDM-based unified, air interface. In order to achieve these goals,further enhancements to LTE and LTE-A are considered in addition todevelopment of the new radio technology for 5G NR networks. The 5G NRwill be capable of scaling to provide coverage (1) to a massive Internetof things (IoTs) with a ULtra-high density (e.g., ˜1M nodes/km²),ultra-low complexity (e.g., ˜10s of bits/sec), ultra-low energy (e.g.,˜10+ years of battery life), and deep coverage with the capability toreach challenging locations; (2) including mission-critical control withstrong security to safeguard sensitive personal, financial, orclassified information, ultra-high reliability (e.g., ˜99.9999%reliability), ultra-low latency (e.g., ˜1 ms), and users with wideranges of mobility or lack thereof; and (3) with enhanced mobilebroadband including extreme high capacity (e.g., ˜10 Tbps/km²), extremedata rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates),and deep awareness with advanced discovery and optimizations.

The 5G NR may be implemented to use optimized OFDM-based waveforms withscalable numerology and transmission time interval (TTI); having acommon, flexible framework to efficiently multiplex services andfeatures with a dynamic, low-latency time division duplex(TDD)/frequency division duplex (FDD) design; and with advanced wirelesstechnologies, such as massive multiple input, multiple output (MIMO),robust millimeter wave (mmWave) transmissions, advanced channel coding,and device-centric mobility. Scalability of the numerology in 5G NR,with scaling of subcarrier spacing, may efficiently address operatingdiverse services across diverse spectrum and diverse deployments. Forexample, in various outdoor and macro coverage deployments of less than3 GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz,for example over 1, 5, 10, 20 MHz, and the like BW. For other variousoutdoor and small cell coverage deployments of TDD greater than 3 GHz,subcarrier spacing may occur with 30 kHz over 80/100 MHz BW. For othervarious indoor wideband implementations, using a TDD over the unlicensedportion of the 5 GHz band, the subcarrier spacing may occur with 60 kHzover a 160 MHz BW. Finally, for various deployments transmitting withmmWave components at a TDD of 28 GHz, subcarrier spacing may occur with120 kHz over a 500 MHz BW.

The scalable numerology of the 5G NR facilitates scalable TTI fordiverse latency and quality of service (QoS) requirements. For example,shorter TTI may be used for low latency and high reliability, whilelonger TTI may be used for higher spectral efficiency. The efficientmultiplexing of long and short TTIs to allow transmissions to start onsymbol boundaries. 5G NR also contemplates a self-contained integratedsubframe design with uplink/downlink scheduling information, data, andacknowledgement in the same subframe. The self-contained integratedsubframe supports communications in unlicensed or contention-basedshared spectrum, adaptive uplink/downlink that may be flexiblyconfigured on a per-cell basis to dynamically switch between uplink anddownlink to meet the current traffic needs.

Various other aspects and features of the disclosure are furtherdescribed below. It should be apparent that the teachings herein may beembodied in a wide variety of forms and that any specific structure,function, or both being disclosed herein is merely representative andnot limiting. Based on the teachings herein one of an ordinary level ofskill in the art should appreciate that an aspect disclosed herein maybe implemented independently of any other aspects and that two or moreof these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. For example,a method may be implemented as part of a system, device, apparatus,and/or as instructions stored on a computer readable medium forexecution on a processor or computer. Furthermore, an aspect maycomprise at least one element of a claim.

Beam management operations are based on the control messages that areperiodically exchanged between transmitter and receiver nodes.Beamforming may be used to bridge the link budget, which may be quitepessimistic at mmWave frequencies due to the heavy propagation loss. TheBS and UE may communicate information using beams, and each of the BSand the UE may steer its energy in a particular direction, reaping arraygains in the process and bridging the link budget. In particular, the BStransmits DL information and the UE receives the DL information usingthe beams. Subsequently, when the UE transmits UL information, the UEmay set the beam weight corresponding to the same direction as thepreviously mentioned beam and transmit UL data with the same beamweights, assuming it has reciprocity.

Beamforming may rely on the design of good beamforming codebooks. Thesecodebooks, however, may perform as designed when the amplitude and phaseat the antennas are reasonably well calibrated. The BS may have a largeamount of antennas, and near-perfect amplitude and phase calibration maydemand a lot of time, complexity, and effort. It may be desirable tomitigate phase and amplitude calibration errors at the BS.

The present disclosure provides techniques for mitigating phase andamplitude calibration errors in communications between a user equipment(UE) and a base station (BS). Due to various factors, the DL and ULchannels may lack reciprocity. With calibration, the adjusted beamweights may be used for receiving and transmitting data. Calibration isthe procedure by which phase and amplitude at every antenna are ensuredto replicate the desired response with a certain excitation. Withoutcalibration, receive beam weights may not produce the correct behavioras intended. Calibration helps correct the phase and amplitudemismatches between transmit and receive circuitry (e.g., due tomismatches in amplifiers, mixers, filters, couplers, etc.). Transmit andreceive beam weights are typically assumed to be reciprocal.Accordingly, without calibration, the receive beam weights may not bereused for the transmission.

While per-antenna calibration can be performed, it can betime-consuming, complex, and manually intensive. Even assuming it isperformed on a per-antenna basis, residual errors in phase and amplitudefor each antenna (e.g., due to measurement precision and time spent oncalibration) may occur. Additionally, with regard to time-varyingcalibration error, calibration is typically done on aper-frequency/subcarrier and per-temperature (value) basis. Due tocomplexity, only a finite number of points may be sampled acrossfrequency and temperature. Once an operating frequency or a number ofcomponent carriers is determined, the only variation(s) come fromtemperature drifts. Due to finite sampling, time-varying phase andamplitude calibration errors may occur.

Aspects of the technology discussed herein can provide several benefits.For example, mitigation of phase and/or amplitude calibration errors atthe BS-side may result in better performance. NR frequency bands mayhave high path loss and may be less stable than the LTE frequency bandsdue to high frequencies. Thus, mitigation of phase and/or amplitudecalibration errors can improve NR network coverage. These benefits andother features are recognized and discussed below.

FIG. 1 illustrates a wireless communication network 100 according tosome embodiments of the present disclosure. The network 100 may be a 5Gnetwork. The network 100 includes a number of base stations (BSs) 105and other network entities. ABS 105 may be a station that communicateswith UEs 115 and may also be referred to as an evolved node B (eNB), anext generation eNB (gNB), an access point, and the like. Each BS 105may provide communication coverage for a particular geographic area. In3GPP, the term “cell” can refer to this particular geographic coveragearea of a BS 105 and/or a BS subsystem serving the coverage area,depending on the context in which the term is used.

ABS 105 may provide communication coverage for a macro cell or a smallcell, such as a pico cell or a femto cell, and/or other types of cell. Amacro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEswith service subscriptions with the network provider. A small cell, suchas a pico cell, would generally cover a relatively smaller geographicarea and may allow unrestricted access by UEs with service subscriptionswith the network provider. A small cell, such as a femto cell, wouldalso generally cover a relatively small geographic area (e.g., a home)and, in addition to unrestricted access, may also provide restrictedaccess by UEs having an association with the femto cell (e.g., UEs in aclosed subscriber group (CSG), UEs for users in the home, and the like).A BS for a macro cell may be referred to as a macro BS. A BS for a smallcell may be referred to as a small cell BS, a pico BS, a femto BS or ahome BS. In the example shown in FIG. 1, the BSs 105 d and 105 e may beregular macro BSs, while the BSs 105 a-105 c may be macro BSs enabledwith one of 3 dimension (3D), full dimension (FD), or massive MIMO. TheBSs 105 a-105 c may take advantage of their higher dimension MIMOcapabilities to exploit 3D beamforming in both elevation and azimuthbeamforming to increase coverage and capacity. The BS 105 f may be asmall cell BS which may be a home node or portable access point. A BS105 may support one or multiple (e.g., two, three, four, and the like)cells.

The network 100 may support synchronous or asynchronous operation. Forsynchronous operation, the BSs may have similar frame timing, andtransmissions from different BSs may be approximately aligned in time.For asynchronous operation, the BSs may have different frame timing, andtransmissions from different BSs may not be aligned in time.

The UEs 115 are dispersed throughout the wireless network 100, and eachUE 115 may be stationary or mobile. A UE 115 may also be referred to asa terminal, a mobile station, a subscriber unit, a station, or the like.A UE 115 may be a cellular phone, a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, atablet computer, a laptop computer, a cordless phone, a wireless localloop (WLL) station, or the like. In one aspect, a UE 115 may be a devicethat includes a Universal Integrated Circuit Card (UICC). In anotheraspect, a UE may be a device that does not include a UICC. In someaspects, the UEs 115 that do not include UICCs may also be referred toas internet of everything (IoE) devices. The UEs 115 a-115 d areexamples of mobile smart phone-type devices accessing network 100 A UE115 may also be a machine specifically configured for connectedcommunication, including machine type communication (MTC), enhanced MTC(eMTC), narrowband IoT (NB-IoT) and the like. The UEs 115 e-115 k areexamples of various machines configured for communication that accessthe network 100. A UE 115 may be able to communicate with any type ofthe BSs, whether macro BS, small cell, or the like. In FIG. 1, alightning bolt (e.g., communication links) indicates wirelesstransmissions between a UE 115 and a serving BS 105, which is a BSdesignated to serve the UE 115 on the downlink and/or uplink, or desiredtransmission between BSs, and backhaul transmissions between BSs.

In operation, the BSs 105 a-105 c may serve the UEs 115 a and 115 busing 3D beamforming and coordinated spatial techniques, such ascoordinated multipoint (CoMP) or multi-connectivity. The macro BS 105 dmay perform backhaul communications with the BSs 105 a-105 c, as well assmall cell, the BS 105 f The macro BS 105 d may also transmits multicastservices which are subscribed to and received by the UEs 115 c and 115d. Such multicast services may include mobile television or streamvideo, or may include other services for providing communityinformation, such as weather emergencies or alerts, such as Amber alertsor gray alerts.

The network 100 may also support mission critical communications withultra-reliable and redundant links for mission critical devices, such asthe UE 115 e, which may be a drone. Redundant communication links withthe UE 115 e may include links from the macro BSs 105 d and 105 e, aswell as links from the small cell BS 105 f Other machine type devices,such as the UE 115 f (e.g., a thermometer), the UE 115 g (e.g., smartmeter), and UE 115 h (e.g., wearable device) may communicate through thenetwork 100 either directly with BSs, such as the small cell BS 105 f,and the macro BS 105 e, or in multi-hop configurations by communicatingwith another user device which relays its information to the network,such as the UE 115 f communicating temperature measurement informationto the smart meter, the UE 115 g, which is then reported to the networkthrough the small cell BS 105 f The network 100 may also provideadditional network efficiency through dynamic, low-latency TDD/FDDcommunications, such as in a vehicle-to-vehicle (V2V)

In some implementations, the network 100 utilizes OFDM-based waveformsfor communications. An OFDM-based system may partition the system BWinto multiple (K) orthogonal subcarriers, which are also commonlyreferred to as subcarriers, tones, bins, or the like. Each subcarriermay be modulated with data. In some instances, the subcarrier spacingbetween adjacent subcarriers may be fixed, and the total number ofsubcarriers (K) may be dependent on the system BW. The system BW mayalso be partitioned into subbands. In other instances, the subcarrierspacing and/or the duration of TTIs may be scalable.

In an embodiment, the BSs 105 can assign or schedule transmissionresources (e.g., in the form of time-frequency resource blocks (RB)) fordownlink (DL) and uplink (UL) transmissions in the network 100. DLrefers to the transmission direction from a BS 105 to a UE 115, whereasUL refers to the transmission direction from a UE 115 to a BS 105. Thecommunication can be in the form of radio frames. A radio frame may bedivided into a plurality of subframes, for example, about 10. Eachsubframe can be divided into slots, for example, about 2. Each slot maybe further divided into mini-slots. In a frequency-division duplexing(FDD) mode, simultaneous UL and DL transmissions may occur in differentfrequency bands. For example, each subframe includes a UL subframe in aUL frequency band and a DL subframe in a DL frequency band. In atime-division duplexing (TDD) mode, UL and DL transmissions occur atdifferent time periods using the same frequency band. For example, asubset of the subframes (e.g., DL subframes) in a radio frame may beused for DL transmissions and another subset of the subframes (e.g., ULsubframes) in the radio frame may be used for UL transmissions.

The DL subframes and the UL subframes can be further divided intoseveral regions. For example, each DL or UL subframe may havepre-defined regions for transmissions of reference signals, controlinformation, and data. Reference signals are predetermined signals thatfacilitate the communications between the BSs 105 and the UEs 115. Forexample, a reference signal can have a particular pilot pattern orstructure, where pilot tones may span across an operational BW orfrequency band, each positioned at a pre-defined time and a pre-definedfrequency. For example, a BS 105 may transmit cell specific referencesignals (CRSs) and/or channel state information—reference signals(CSI-RSs) to enable a UE 115 to estimate a DL channel. Similarly, a UE115 may transmit sounding reference signals (SRSs) to enable a BS 105 toestimate a UL channel. Control information may include resourceassignments and protocol controls. Data may include protocol data and/oroperational data. In some embodiments, the BSs 105 and the UEs 115 maycommunicate using self-contained subframes. A self-contained subframemay include a portion for DL communication and a portion for ULcommunication. A self-contained subframe can be DL-centric orUL-centric. A DL-centric subframe may include a longer duration for DLcommunication than UL communication. A UL-centric subframe may include alonger duration for UL communication than DL communication.

In some embodiments, the BS 105 can coordinate with the UE 115 tocooperatively schedule, beamform, and/or transmit data in the network100. Substantial gain may be achieved through greater use of a multipleantenna system. In mmWave access, for example, a large number of antennaelements may be used to take advantage of shorter wavelengths, and toenable beamforming and beam-tracking. The higher the frequencies, thegreater the propagation and penetration losses may be.

Beamforming techniques may be used to increase the signal level receivedby a device and to avoid transmission losses when using, for example,mmWave frequencies. A beamformer enhances energy over itstargeted/intended direction(s), obtaining a certain antenna gain in agiven direction while having attenuation in others. Beamforming combinessignals from multiple antenna elements in an antenna array, so that thecombined signal level increases when several signal phases align(constructive interference). Each antenna array may include a pluralityof antenna elements. The signals from each antenna element aretransmitted with a slightly different phase (delay) to produce a narrowbeam directed towards the receiver.

Due to various factors, the DL and UL channels may lack reciprocity forvarious reasons. Example scenarios in which the DL and UL channels maylack reciprocity include use of poor RF components on either the DL orthe UL, poor calibration efforts to adjust the DL/UL circuitry, drift ofcomponent behavior with time, temperature, and other parameters, etc.The calibration procedure may involve determining nominal differencesbetween the DL and UL circuitry.

While per-antenna calibration can be performed, it can betime-consuming, complex, and manually intensive. Even assuming it isperformed on a per-antenna basis, residual errors in phase and amplitudefor each antenna (e.g., due to measurement precision and time spent oncalibration) may occur. Additionally, with regard to time-varyingcalibration errors, calibration is typically done on aper-frequency/subcarrier and per-temperature (value) basis. Due tocomplexity, only a finite number of points may be sampled acrossfrequency and temperature. Once an operating frequency or number ofcommon carriers is determined, the only variation(s) may come fromtemperature drifts.

Due to finite sampling, time-varying phase and amplitude calibrationerrors may occur. In terms of phase calibration error, it may bereasonable to assume that the phase at the i-th antenna at any point intime satisfies the following equation:ϕ_(i)={circumflex over (ϕ)}_(i)=ε_(i),  (1)where ϕ_(i) represents a measured phase, {circumflex over (ϕ)}_(i)represents a true phase, and ε_(i) represents a phase error incalibration.

The phase calibration error may be uniformly distributed in +/−q degreesin accordance with the following equation:ε_(i)˜∪(−q,q),  (2)

The phase calibration error may be uniformly distributed with some smallangular resolution of +/−q degrees. In an example, q is 5°, which may bereasonable based on low calibration, but may result in an approximateerror of +/−20° for low-complexity calibration.

In terms of amplitude calibration error, it may be reasonable to assumethat the amplitude at the i-th antenna at any point in time satisfiesthe following equation:α_(i)={circumflex over (α)}_(i)+

_(i),  (3)where α_(i) represents a measured amplitude, {circumflex over (α)}_(i)represents a true amplitude, and ζ_(i) represents an amplitudecalibration error in calibration.

The amplitude calibration error may be uniformly distributed in +/−Aamplitude units in accordance with the following equation:

_(i)˜∪(−A,A),  (4)

The amplitude calibration error may be uniformly distributed with somesmall angular resolution of

+/−A amplitude units.

Another impairment aside from the phase and amplitude calibration errorsmay involve the failure of a certain fraction of the antennas. Randomantenna failures may occur, where α_(i) may be assumed to be zero forsome indices. In an example, if a certain percentage of antennas in a32×4 antenna array at the BS-side are dropped or failed (e.g., one, two,five, ten, fifteen, and twenty percent), the worst-case performance maydegrade dramatically. In this example, the smallest percentage drop maybe one percent. If five percent of the antennas are dropped, theworst-case gain in coverage area may go from about −6 dB to about −15dB. In an example, an antenna is “dropped” if it is excluded from beingused for transmitting a communication signal, thus decreasing the numberof antennas used for transmitting the communication signal. Conversely,an antenna is “added” if it is included (and was previously excluded)for use in transmitting a communication signal, thus increasing thenumber of antennas used for transmitting the communication signal. Thearray is reconfigured for optimal phase/amplitude or for compensatingthe phase/amplitude calibration errors for one or more beams in aparticular sector.

Additionally, the aforementioned errors may be time-varying. Forexample, at one point in time, the errors may be between +/−5°, but ifthe array at the BS 105 heats up and the temperature drifts, theexpected nominal temperature may drift away by about 10°. If thecalibration is not performed using that actual temperature (rather thanthe expected temperature), a +/−20° error may result. Moreover, if thesize of the BS 105's antenna array is large, a large amount of netaccumulation due to the above-mentioned impairments may occur.

A codebook includes beam weights for a collection of beams used to coverthe BS 105's coverage area. A codebook may be designed a priori, and theBS may use the codebook to apply a specific set of beam weights to pointsignals in a certain direction. For example, an array that covers 120°in azimuth and 50° in elevation may use four beams. Each beam mayinclude a collection of beam weights applied to the antennas. A firstbeam may point in a first direction, a second beam may point in a seconddirection, a third beam may point in a third direction, and a fourthbeam may point in a fourth direction. Each of these four beams covers adistinct region of the coverage area, and in particular, the BS may usethe four beams to cover the 120°×50° coverage area. The latencyassociated with the initial acquisition, refinement, or otherbeamforming procedure may be dependent on the codebook size (e.g., four,eight, sixteen, thirty-two). The greater the codebook size, the morerefined the link may be, resulting in a better beamforming gain.

With regard to codebooks, even a small phase calibration error +/−5° mayresult in substantial worst-case gain deterioration for a small codebooksize. Additionally, a moderate phase calibration error +/−20° can resultin significantly large performance deterioration. Significantdeterioration in performance may result from poor amplitude calibrationor from a substantial fraction of antennas being lost. The aboveimpairments may have a larger effect on small-sized codebooks comparedto large-sized codebooks due to more redundancy in beam weights in thelatter. For example, for a size four codebook, a worst-case gain over a120°×50° coverage area may be poor because a large array size is used tocover a huge area with small number of beams. For good coverage, thelatency may be reduced. If the size four codebook entry has a +/−5°error uniformly distributed, the cumulative distribution function (CDF)of the worst-case gain may range from about −5.5 to about −8 dB. If thesize four codebook entry has a +/−25° error uniformly distributed, theworst-case gain may range from about −7 to about −15 dB. The greater thecalibration error, the worse the performance may be in terms ofworst-case gain for the coverage area. The BS is unware of where the UEmay be located and may be interested in improving the performance, evenfor the worst-case scenario.

It may be desirable to mitigate phase and amplitude calibration errorsat the BS. In some examples, mitigation of phase and amplitudecalibration errors may involve modifying the array size, transmissionpower levels, and/or a beam codebook at the BS-side.

FIG. 2 illustrates a communication method 200 according to someembodiments of the present disclosure. As shown in diagram 200, a set ofinput parameters 202 and a set of control inputs 210 are associated witha BS 205. A set of input parameters 202 and set of control inputs 210may be used to modify the antenna array size or codebook size fortransmitting data. Set of input parameters 202 may include a size ofantenna array 204, a coverage area of array 206, and a codebook size208, among other input parameters. Set of control inputs 210 may includea maximal phase calibration error q 212, a maximal amplitude calibrationerror A 214, and a fraction of antennas lost 216, among other controlinputs.

The BS 205 includes a plurality of antenna elements 220. In an example,the plurality of antenna elements includes 128 antenna elements (32×4antenna array), and the codebook size is four. A codebook size of fouris small and constrained compared to larger sizes (e.g., eight, sixteen,or thirty-two). Rather than use the 32×4 array, the BS 204 may use areduced size array (e.g., 16×4 antenna array) to cover the same coveragearea 206 and with the same codebook size 208. The BS 205 may increasethe transmit power to be within the effective isotropic radiated power(EIRP)/total radiated power (TRP) limit for transmission due to the lostpeak array gain from the antenna array size reduction.

In the ideal case of no phase calibration error, use of the 16×4 antennaarray by the BS 205 in terms of performance may be poorer than using the32×4 antenna array. However, by reducing the antenna array size from32×4 to 16×4, the performance may be more robust to phase calibrationerrors. For example, if the BS 205 performed with a +/−10° error withthe 32×4 array size, the use of the 16×4 array size with the same +/−10°error may not cause the worst-case scenario to suffer too much. In thepresence of a phase calibration error, the 16×4 antenna array providesbetter performance than the 32×4 antenna array by a 3 dB boost. In thisexample, the peak powers for these two arrays may match, but the 16×4antenna array provides more robustness to the worst-case power scenario.

If the BS 205 uses a codebook that is small in size, the design may notprovide for robustness to phase and amplitude calibration errors. If theBS 205 uses a large array, a number of antennas from the array may beleft unused (e.g., 50% of the antennas), resulting in the loss of 3 dBin terms of peak array gain. The loss may be compensated by increasingthe EIRP by 3 dB such that the net power steered in a particulardirection stays the same.

The BS 205 may receive feedback 230 from one or more UEs 215 todetermine whether to modify the antenna array size and/or the powertransmit level. Modification may occur to support changing an effectivearray size (e.g., for broadened beams). The feedback 230 may be anindication to the BS 205 to modify the first number and the firsttransmission power level for subsequent signal transmissions. Thefeedback 230 from one or more UEs may guide the BS 205 in itsdetermination of whether to modify the number antenna elements and/orthe transmission power level for future signal transmissions. In anexample, the feedback 230 is a measurement report including at least oneof a reference signal received power (RSRP), a reference signal receivedquality (RSRQ), a received signal strength indicator (RSSI), asignal-to-interference-plus-noise ratio (SINR), or a signal-to-noiseratio (SNR) from one or more UEs 215. It may be advantageous for a UE toprovide this type of information in a measurement report that is sent tothe BS because it provides the BS with feedback the UE's experience. Forexample, if the BS is provided with an indication (via measurementreports) that multiple UEs are experiencing poor RSRP levels, the BS maydetermine that the poor performance is due to phase and/or amplitudecalibration errors. To mitigate these calibration errors, the BS maymodify the array size and/or the transmission power level for futuresignal transmissions.

With reference to FIG. 2, the BS 205 may have sufficient processingpower to determine a mitigation strategy 240. A mitigation strategy mayinclude determining whether to modify the array size and thetransmission power level for future signal transmissions. In thisexample, the BS may modify the transmission power level and the arraysize (e.g., by decreasing the array size and increasing the transmissionpower level if the error estimate is large or by increasing the arraysize and decreasing the transmission power level if the error estimateis small) based on the feedback from one or more UEs.

The BS may modify the transmission power level and the array size basedon an aggregate of power reports of multiple UEs (e.g., UE actionrequests and phase/amplitude calibration error information). The BS mayadjust/refine the codebook based on the feedback. For example, the BSmay go from using a size four codebook to a size eight or a size sixteencodebook. Using information from the UEs in the coverage area, the BSmay perform a codebook adjustment at the BS. Thus, codebook changes canbe done as a function of information contained in aggregated UE reports.If the net performance at the UEs improve, the BS codebook adjustment isin the correct direction and iterates this process to improve thecodebook. Additionally, the BS may improve the calibration accuracy witha built-in test mode (e.g., an online/mission mode calibration orself-test).

A self-test may include reviewing operational characteristics andadjusting antenna array usage parameters based on reviewing results ofthe self-test. By performing a self-test, a BS can improve operationalperformance or perform in accordance with desired network designconditions. Self-test details may be stored in a memory at the BS and/orperiodically updated throughout operations as desired.

FIG. 3 illustrates a communication method 300 according to someembodiments of the present disclosure. FIG. 3 includes the BS 205, theset of input parameters 202, and the set of control inputs 210. The BS205 is coupled to a transmission point 302 via a link 304. Thetransmission point 302 includes the plurality of antenna elements 220.In some examples, the link 304 is an optical fiber link between the BSand the transmission point 302. The BS 205 may forward feedback 230 fromone or more UEs to the transmission point 302.

With reference to FIG. 3, the BS 205 may have little in terms ofcomputational intelligence. For example, the BS may be small and a largeantenna array (e.g., 32×4) may be unable to fit in the BS. In thisexample, the BS may forward to a transmission point (e.g., server) thefeedback (e.g., measurement report) from the UE and instantaneousinformation on phase and/or amplitude calibration errors (e.g.,temperature estimate and a lookup table for calibration interpolationerror). The transmission point 302 processes the information forwardedby the BS and feeds the mitigation strategy 240 back to the BS. Althoughnot shown, the transmission point 302 may be used by one or more BS formitigating amplitude and phase calibration errors. The transmissionpoint 302 may be, for example, a server, a network-level device, orother device.

In some examples, if a sufficient number of UEs report a power metric(e.g., RSRP, RSRQ, RSSI, SINR, or SNR) below a particular threshold, theBS may modify the array size and the transmission power level (e.g., bydecreasing the array size and increasing the transmission power level orby increasing the array size and decreasing the transmission power toimprove the BS's worst-case coverage). In some examples, thetransmission point may suggest a codebook adjustment (e.g., increase ordecrease the codebook size) or refinement. In some examples, thetransmission point improves calibration accuracy with a built-in testmode (e.g., an online mode/mission mode calibration).

FIG. 4 is a block diagram of an exemplary BS 400 according toembodiments of the present disclosure. The BS 400 may be a BS 105 asdiscussed above. As shown, the BS 400 may include a processor 402, amemory 404, a calibration module 408, a report module 409, a transceiver410 including a modem subsystem 412 and a RF unit 414, and one or moreantennas 416. These elements may be in direct or indirect communicationwith each other, for example via one or more buses.

The processor 402 may have various features as a specific-typeprocessor. For example, these may include a CPU, a DSP, an ASIC, acontroller, a FPGA device, another hardware device, a firmware device,or any combination thereof configured to perform the operationsdescribed herein. The processor 402 may also be implemented as acombination of computing devices, e.g., a combination of a DSP and amicroprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The memory 404 may include a cache memory (e.g., a cache memory of theprocessor 402), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, asolid state memory device, one or more hard disk drives, memristor-basedarrays, other forms of volatile and non-volatile memory, or acombination of different types of memory. In some embodiments, thememory 404 may include a non-transitory computer-readable medium. Thememory 404 may store instructions 406. The instructions 406 may includeinstructions that, when executed by the processor 402, cause theprocessor 402 to perform operations described herein. Instructions 406may also be referred to as code. The terms “instructions” and “code”should be interpreted broadly to include any type of computer-readablestatement(s). For example, the terms “instructions” and “code” may referto one or more programs, routines, sub-routines, functions, procedures,etc. “Instructions” and “code” may include a single computer-readablestatement or many computer-readable statements.

Each of calibration module 408 and report module 409 may be implementedvia hardware, software, or combinations thereof. For example, each ofcalibration module 408 and report module 409 may be implemented as aprocessor, circuit, and/or instructions 406 stored in the memory 404 andexecuted by the processor 402.

Each of calibration module 408 and report module 409 may be used forvarious aspects of the present disclosure. For example, the calibrationmodule 408 may be configured to transmit, via an antenna array includinga plurality of antenna elements, a first communication signal using afirst number of the plurality of antenna elements and a firsttransmission power level. The report module 409 may be configured toreceive, from at least one UE, a measurement report based on the firstcommunication signal. The calibration module 408 may perform calibrationfor the mismatch based on the measurement report. For example, thecalibration module 408 may increase the number of antenna elements anddecrease the transmission power level for future communication signaltransmissions. In another example, the calibration module 408 maydecrease the number of antenna elements and increase the transmissionpower level for future communication signal transmissions.

The calibration module 408 may be further configured to transmit asecond communication signal using a second number of the plurality ofantenna elements and a second transmission power level based on themeasurement report. At least one of the first number of the plurality ofantenna elements is different from the second number of the plurality ofantenna elements, or at least one of the first transmission power levelis different from the second transmission power level. The calibrationmodule 408 may be further configured to transmit the first communicationsignal beam, a beam codebook, adjust or refine the beam code book basedon the measurement report, and transmit the second communication signalbased on the adjusted beam code book. Mechanisms for mitigating phaseand amplitude calibration errors for communications between a BS and aUE are described in greater detail herein.

As shown, the transceiver 410 may include the modem subsystem 412 andthe RF unit 414. The transceiver 410 can be configured to communicatebi-directionally with other devices, such as the UEs 115 and/or anothercore network element. The modem subsystem 412 may be configured tomodulate and/or encode data from the memory 404, the calibration module408, and/or the report module 409 according to a modulation and codingscheme (MCS), e.g., a LDPC coding scheme, a turbo coding scheme, aconvolutional coding scheme, a digital beamforming scheme, etc. The RFunit 414 may be configured to process (e.g., perform analog to digitalconversion or digital to analog conversion, etc.) modulated/encoded datafrom the modem subsystem 412 (on outbound transmissions) or oftransmissions originating from another source such as a UE 115. The RFunit 414 may be further configured to perform analog beamforming inconjunction with the digital beamforming. Although shown as integratedtogether in transceiver 410, the modem subsystem 412 and the RF unit 414may be separate devices that are coupled together at the BS 105 toenable the BS 105 to communicate with other devices.

The RF unit 414 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may contain one ormore data packets and other information), to the antennas 416 fortransmission to one or more other devices. The antennas 416 may furtherreceive data messages transmitted from other devices and provide thereceived data messages for processing and/or demodulation at thetransceiver 410. The antennas 416 may include multiple antennas ofsimilar or different designs in order to sustain multiple transmissionlinks.

FIG. 5 is a block diagram of an exemplary UE 500 according toembodiments of the present disclosure. The UE 500 may be a UE 115 asdiscussed above. As shown, the UE 500 may include a processor 502, amemory 504, a calibration module 508, a report module 509, a transceiver510 including a modem subsystem 512 and a radio frequency (RF) unit 514,and one or more antennas 516. These elements may be in direct orindirect communication with each other, for example via one or morebuses.

The processor 502 may include a central processing unit (CPU), a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a controller, a field programmable gate array (FPGA) device,another hardware device, a firmware device, or any combination thereofconfigured to perform the operations described herein. The processor 502may also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The memory 504 may include a cache memory (e.g., a cache memory of theprocessor 502), random access memory (RAM), magnetoresistive RAM (MRAM),read-only memory (ROM), programmable read-only memory (PROM), erasableprogrammable read only memory (EPROM), electrically erasableprogrammable read only memory (EEPROM), flash memory, solid state memorydevice, hard disk drives, other forms of volatile and non-volatilememory, or a combination of different types of memory. In an embodiment,the memory 504 includes a non-transitory computer-readable medium. Thememory 504 may store instructions 506. The instructions 506 may includeinstructions that, when executed by the processor 502, cause theprocessor 502 to perform the operations described herein with referenceto the UEs 115 in connection with embodiments of the present disclosure.Instructions 506 may also be referred to as code, which may beinterpreted broadly to include any type of computer-readablestatement(s) as discussed above with respect to FIG. 4.

Each of calibration module 508 and report module 509 may be implementedvia hardware, software, or combinations thereof. For example, each ofcalibration module 508 and report module 509 may be implemented as aprocessor, circuit, and/or instructions 506 stored in the memory 504 andexecuted by the processor 502.

Each of calibration module 508 and report module 509 may be used forvarious aspects of the present disclosure. For example, the calibrationmodule 508 may be configured to receive a first communication sign froma BS (e.g., the BSs 105). The report module 509 may be configured totransmit to the BS, a request to change at least one of an antenna arraysize at the base station, a transmit power level at the base station,and/or a beam codebook based on the first communication signal. Thecalibration module 508 may be configured to receive from the basestation, a second communication signal in response to the request.

As shown, the transceiver 510 may include the modem subsystem 512 andthe RF unit 514. The transceiver 510 can be configured to communicatebi-directionally with other devices, such as the BSs 105. The modemsubsystem 512 may be configured to modulate and/or encode the data fromthe memory 504, the calibration module 508, and/or the report module 509according to a MCS, e.g., a low-density parity check (LDPC) codingscheme, a turbo coding scheme, a convolutional coding scheme, a digitalbeamforming scheme, etc. The RF unit 514 may be configured to process(e.g., perform analog to digital conversion or digital to analogconversion, etc.) modulated/encoded data from the modem subsystem 512(on outbound transmissions) or of transmissions originating from anothersource such as another UE or a BS 105. The RF unit 514 may be furtherconfigured to perform analog beamforming in conjunction with the digitalbeamforming. Although shown as integrated together in transceiver 510,the modem subsystem 512 and the RF unit 514 may be separate devices thatare coupled together at the UE 115 to enable the UE 115 to communicatewith other devices.

The RF unit 514 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may contain one ormore data packets and other information), to the antennas 516 fortransmission to one or more other devices. The antennas 516 may furtherreceive data messages transmitted from other devices. The antennas 516may provide the received data messages for processing and/ordemodulation at the transceiver 510. The antennas 516 may includemultiple antennas of similar or different designs in order to sustainmultiple transmission links. The RF unit 514 may configure the antennas516.

FIG. 6 illustrates a signaling diagram of a method 600 for mitigatingcalibration errors according to some embodiments of the presentdisclosure. Steps of the method 600 can be executed by computing devices(e.g., a processor, processing circuit, and/or other suitable component)of wireless communication devices, such as the BSs 105 and 400 and theUEs 115 and 500. The method 600 can be better understood with referenceto FIGS. 2 and 3. As illustrated, the method 600 includes a number ofenumerated steps, but embodiments of the method 600 may includeadditional steps before, after, and in between the enumerated steps. Insome embodiments, one or more of the enumerated steps may be omitted orperformed in a different order. The method 600 illustrates one BS andone standalone UE for purposes of simplicity of discussion, though itwill be recognized that embodiments of the present disclosure may scaleto many more UEs and/or BSs.

At step 602, a BS 605 transmits a first communication signal using afirst number of a plurality of antenna elements and a first transmissionpower level to a UE 615. In an example, the BS 605 includes an antennaarray including the plurality of antenna elements. In this example, theBS 605 determines the first number of the plurality of antenna elementsand/or the first transmission power level based on at least one of asize of the antenna array, a coverage area for the antenna array, acodebook size, a latency, a phase calibration error, an amplitudecalibration error, or a fraction of failed antenna elements. In anotherexample, a transmission point (e.g., transmission point 302 in FIG. 3)includes an antenna array including the plurality of antenna elementsand is remote from the BS. In this example, the BS transmits the firstcommunication signal to a UE via the transmission point.

The UE 615 receives the first communication signal from the BS 605. Atstep 604, the UE 615 transmits feedback based on the received firstcommunication signal, the feedback including an indication to modify thefirst number and the first transmission power level for a subsequentsignal transmission. In an example, the feedback includes a request tochange at least one of an antenna array size at the BS 605 or a transmitpower level at the BS 605 based on the first communication signal. In anexample, the feedback includes a measurement report including at leastone of a RSRP, a RSRQ, a RSSI, a SINR, or a SNR corresponding to a bestbeam pair from one or more UEs.

The BS 205 may compare the measurement report to a threshold. In anexample, the measurement report includes a RSRP, RSRQ, RSSI, SINR, orSNR metric corresponding to the best beam pair from the UE. If a certainfraction of the UE's power level reports satisfies the threshold (e.g.,is below or above the threshold), the BS 205 may modify the number ofthe plurality of antenna elements and/or the transmission power levelfor future signal transmissions. The BS 605 may determine the secondnumber of the plurality of antenna elements and/or the secondtransmission power level based on a comparison between the measurementreport and the threshold.

At step 606, the BS 605 transmits a second communication signal based onthe feedback to the UE 615, the second communication signal using asecond number of the plurality of antenna elements and a secondtransmission power level. The BS 605 may use a combination of thefeedback from one or more UEs, phase calibration error information,and/or amplitude calibration error information in its decision to modifythe number of antenna elements and the transmission power level forfuture communication signal transmissions.

The BS 605 may determine the second number of the plurality of antennaelements and the second transmission power level based on the feedback.In an example, the BS 605 decreases the array size and increases thetransmission power level such that the first number of the plurality ofantenna elements is less than the second number of the plurality ofantenna elements and the first transmission power level is greater thanthe second transmission power level. In another example, the BS 605increases the array size and decreases the transmission power level suchthat the first number of the plurality of antenna elements is greaterthan the second number of the plurality of antenna elements and thefirst transmission power level is less than the second transmissionpower level. Additionally, the BS 605 may transmit the secondcommunication signal by applying a codebook including beamformingweights. The BS 605 may adjust the beamforming weights in the codebookbased on the feedback (e.g., measurement report).

FIG. 7 is a flow diagram of a communication method 700 according toembodiments of the present disclosure. Steps of the method 700 can beexecuted by a computing device (e.g., a processor, processing circuit,and/or other suitable component) of a wireless communication device,such as the BSs 105 and 400. The method 700 may employ similarmechanisms as in the methods 200 and 300 described with respect to FIGS.2 and 3, respectively. As illustrated, the method 700 includes a numberof enumerated steps, but embodiments of the method 700 may includeadditional steps before, after, and in between the enumerated steps. Insome embodiments, one or more of the enumerated steps may be omitted orperformed in a different order.

At step 710, the method 700 includes transmitting, by a base station viaan antenna array including a plurality of antenna elements, a firstcommunication signal using a first number of the plurality of antennaelements and a first transmission power level. In an example, the BSincludes an antenna array including the plurality of antenna elements.In this example, the BS determines the first number of the plurality ofantenna elements and/or the first transmission power level based on atleast one of a size of the antenna array, a coverage area for theantenna array, a codebook size, a latency, a phase calibration error, anamplitude calibration error, or a fraction of failed antenna elements.In another example, a transmission point (e.g., transmission point 302in FIG. 3) includes an antenna array including the plurality of antennaelements and is remote from the BS. In this example, the BS transmitsthe first communication signal to a UE via the transmission point.

At step 720, the method 700 includes receiving, by the base station fromat least one user equipment, a measurement report based on the firstcommunication signal. In an example, the measurement report includes atleast one of a RSRP, a RSRQ, a RSSI, a SINR, or a SNR metriccorresponding to a best beam pair from a UE. The BS may receive multiplemeasurement reports from multiple UEs.

At step 730, the method 700 includes transmitting, by the base station,a second communication signal using a second number of the plurality ofantenna elements and a second transmission power level based on the oneor more measurement reports, where the at least one of the first numberof the plurality of antenna elements is different from the second numberof the plurality of antenna elements or the first transmission powerlevel is different from the second transmission power level. The BS maydetermine the second number of the plurality of antenna elements and/orthe second transmission power level based on a comparison between themeasurement report and a threshold. In an example, the BS determines tomodify the number of plurality of antenna elements used for transmittingthe second communication signal from the first number to the secondnumber and determines to modify the transmission power level used fortransmitting the second communication signal from the first the firsttransmission power level to the second transmission power level.

The BS may compare the data included in the one or more measurementreports to the threshold. In an example, a measurement report includesat least one of a RSRP, RSRQ, RSSI, SINR, or SNR metric corresponding tothe best beam pair from the UE. If a certain fraction of the UE's powerlevel reports satisfies the threshold (e.g., is below or above thethreshold), the BS may modify the number of the plurality of antennaelements and/or the transmission power level for future signaltransmissions. In an example, the BS may increase the number of antennaelements and decrease the transmission power level for futurecommunication signal transmissions. In another example, the BS maydecrease the number of antenna elements and increase the transmissionpower level for future communication signal transmissions.

In some examples, a plurality of UEs sends the BS a measurement report.Accordingly, the BS receives a plurality of measurement reports. The BSmay aggregate the plurality of measurement reports and determine, basedon the aggregated measurement reports, to transmit the secondcommunication signal using the second number of the plurality of antennaelements and the second transmission power level. The changes made toadjust the antenna element array size may happen at any time and may bebased on feedback from one or more UEs (e.g., based on a measurementreport).

FIG. 8 is a flow diagram of a communication method 800 according toembodiments of the present disclosure. Steps of the method 800 can beexecuted by a computing device (e.g., a processor, processing circuit,and/or other suitable component) of a wireless communication device,such as the UEs 115 and 500. The method 800 may employ similarmechanisms as in the methods 200 and 300 described with respect to FIGS.2 and 3, respectively. As illustrated, the method 800 includes a numberof enumerated steps, but embodiments of the method 800 may includeadditional steps before, after, and in between the enumerated steps. Insome embodiments, one or more of the enumerated steps may be omitted orperformed in a different order.

At step 810, the method 800 includes receiving, by a user equipment froma base station, a first communication signal. In an example, the UEreceives the first communication signal from the BS via a link thatconnects the UE and the BS. In another example, the UE receives thefirst communication signal from the BS via the transmission point.

At step 820, the method 800 includes transmitting, by the user equipmentto the base station, a request to change at least one of an antennaarray size at the base station or a transmit power level at the basestation based on the first communication signal. In an example, the UEtransmits a request to change the antenna array size at the BS based onthe first communication signal. In another example, the UE transmits arequest to change the transmit power level at the base BS based on thefirst communication signal.

At step 830, the method 800 includes receiving, by the user equipmentfrom the base station, a second communication signal in response to therequest. In an example, the BS modifies the antenna array size and/orthe transmit power level at the base station in accordance with therequest and transmits the second communication signal using the modifiedantenna array size and/or the transmit power level.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more of”) indicates an inclusivelist such that, for example, a list of [at least one of A, B, or C]means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

Embodiments of the present disclosure include a method of wirelesscommunication, including transmitting, by a base station via an antennaarray including a plurality of antenna elements, a first communicationsignal using a first number of the plurality of antenna elements and afirst transmission power level; receiving, by the base station from atleast one user equipment, a measurement report based on the firstcommunication signal; and transmitting, by the base station, a secondcommunication signal using a second number of the plurality of antennaelements and a second transmission power level based on the measurementreport, wherein the at least one of the first number of the plurality ofantenna elements is different from the second number of the plurality ofantenna elements or the first transmission power level is different fromthe second transmission power level.

The method further includes receiving the measurement report byreceiving at least one of a RSRP, a RSRQ, a RSSI, a SINR, or a SNR fromat least one UE. The method further includes receiving the measurementreport by receiving a request to change at least one of the first numberof the plurality of antenna elements at the base station or the firsttransmission power level at the base station. The method furtherincludes determining, by the base station, the first number of theplurality of antenna elements based on at least one of a size of theantenna array, a coverage area for the antenna array, a codebook size, alatency, a phase calibration error, an amplitude calibration error, or afraction of failed antenna elements. The method further includesdetermining, by the base station, the first transmission power levelbased on at least one of a size of the antenna array, a coverage areafor the antenna array, a codebook size, a latency, a phase calibrationerror, an amplitude calibration error, or a fraction of failed antennaelements.

The method further includes determining, by the base station, the secondnumber of the plurality of antenna elements based on a comparisonbetween the measurement report and a threshold. The method furtherincludes determining, by the base station, the second transmission powerlevel based on a comparison between the measurement report and athreshold. In an example, the first number of the plurality of antennaelements is greater than the second number of the plurality of antennaelements, and the first transmission power level is less than the secondtransmission power level. In another example, the first number of theplurality of antenna elements is less than the second number of theplurality of antenna elements, and the first transmission power level isgreater than the second transmission power level.

The method further includes transmitting the second communication signalby applying a codebook including beamforming weights. The method furtherincludes adjusting, by the base station, the beamforming weights in thecodebook based on the measurement report. The method further includestransmitting the first communication signal by transmitting the firstcommunication signal to a UE via a transmission point remote from theBS, the transmission point including the antenna array.

Embodiments of the present disclosure further include a method ofwireless communication, including receiving, by a user equipment from abase station, a first communication signal; transmitting, by the userequipment to the base station, a request to change at least one of anantenna array size at the base station or a transmit power level at thebase station based on the first communication signal; and receiving, bythe user equipment from the base station, a second communication signalin response to the request.

The method further includes receiving the first communication signal byreceiving the first communication signal from a transmission pointremote from the base station. The method further includes transmittingto the base station, a metric corresponding to a best beam pair at theuser equipment, where the second communication signal is in response tothe metric. The metric is at least one of a RSRP, a RSRQ, a RSSI, aSINR, a SNR corresponding to the best beam pair at the UE.

Embodiments of the present disclosure further include a method ofwireless communication, including receiving, by a user equipment from abase station, a first communication signal; transmitting, by the userequipment to the base station, a first request to change an antennaarray size at the base station based on the first communication signal;and receiving, by the user equipment from the base station, a secondcommunication signal in response to the first request. In some aspects,the method may also include transmitting, by the user equipment to thebase station, a second request to change a transmit power level at thebase station based on the first communication signal, where receivingthe second communication may be in response to the second request. Insome aspects, the method may also include receiving, by the userequipment from the base station, a third communication signal;transmitting, by the user equipment to the base station, a secondrequest to change a transmit power level at the base station based onthe third communication signal; and receiving, by the user equipmentfrom a base station, a fourth communication signal in response to thesecond request.

Embodiments of the present disclosure further include an apparatusincluding a transceiver configured to transmit, by a base station via anantenna array including a plurality of antenna elements, a firstcommunication signal using a first number of the plurality of antennaelements and a first transmission power level; receive, by the basestation from at least one user equipment, a measurement report based onthe first communication signal; and transmit, by the base station, asecond communication signal using a second number of the plurality ofantenna elements and a second transmission power level based on themeasurement report, where the at least one of the first number of theplurality of antenna elements is different from the second number of theplurality of antenna elements or the first transmission power level isdifferent from the second transmission power level.

The transceiver is further configured to receive the measurement reportby receiving at least one of a RSRP, a RSRQ, a RSSI, a SINR, or a SNRfrom at least one UE. The transceiver may be further configured toreceive the measurement report by receiving a request to change at leastone of the first number of the plurality of antenna elements at the basestation or the first transmission power level at the base station.

The apparatus further includes a processor configured to determine thefirst number of the plurality of antenna elements based on at least oneof a size of the antenna array, a coverage area for the antenna array, acodebook size, a latency, a phase calibration error, an amplitudecalibration error, or a fraction of failed antenna elements. Theprocessor is further configured to determine the first transmissionpower level based on at least one of a size of the antenna array, acoverage area for the antenna array, a codebook size, a latency, a phasecalibration error, an amplitude calibration error, or a fraction offailed antenna elements.

The processor is further configured to determine the second number ofthe plurality of antenna elements based on a comparison between themeasurement report and a threshold. The processor is further configuredto determine the second transmission power level based on a comparisonbetween the measurement report and a threshold. In an example, the firstnumber of the plurality of antenna elements is greater than the secondnumber of the plurality of antenna elements, and the first transmissionpower level is less than the second transmission power level. In anotherexample, the first number of the plurality of antenna elements is lessthan the second number of the plurality of antenna elements, and thefirst transmission power level is greater than the second transmissionpower level.

The transceiver is further configured to transmit the secondcommunication signal by applying a codebook including beamformingweights. The processor is further configured to adjust the beamformingweights in the codebook based on the measurement report. The transceiveris further configured to transmit the first communication signal bytransmitting the first communication signal to a UE via a transmissionpoint remote from the BS, the transmission point including the antennaarray.

Embodiments of the present disclosure further include an apparatusincluding a transceiver configured to receive, by a user equipment froma base station, a first communication signal; transmit, by the userequipment to the base station, a request to change at least one of anantenna array size at the base station or a transmit power level at thebase station based on the first communication signal; and receive, bythe user equipment from the base station, a second communication signalin response to the request.

The transceiver is further configured to receive the first communicationsignal from a transmission point remote from the base station. Thetransceiver is further configured to transmit to the base station, ametric corresponding to a best beam pair at the user equipment, wherethe second communication signal is in response to the metric. The metricis at least one of a RSRP, a RSRQ, a RSSI, a SINR, a SNR correspondingto the best beam pair at the UE.

Embodiments of the present disclosure further include an apparatusincluding a transceiver configured to receive, by a user equipment froma base station, a first communication signal; transmit, by the userequipment to the base station, a first request to change a transmitpower level at the base station based on the first communication signal;and receive, by the user equipment from the base station, a secondcommunication signal in response to the first request. In some aspects,the transceiver is configured to receive, by the user equipment from thebase station, a third communication signal; transmit, by the userequipment to the base station, a second request to change an antennaarray size at the base station based on the third communication signal;and receive, by the user equipment from the base station, a fourthcommunication signal in response to the second request.

Embodiments of the present disclosure further include acomputer-readable medium having program code recorded thereon, theprogram code including code for transmitting via an antenna arrayincluding a plurality of antenna elements, a first communication signalusing a first number of the plurality of antenna elements and a firsttransmission power level; code for receiving from at least one userequipment, a measurement report based on the first communication signal;and code for transmitting a second communication signal using a secondnumber of the plurality of antenna elements and a second transmissionpower level based on the measurement report, where the at least one ofthe first number of the plurality of antenna elements is different fromthe second number of the plurality of antenna elements or the firsttransmission power level is different from the second transmission powerlevel.

The computer-readable medium further includes code for receiving atleast one of a RSRP, a RSRQ, a RSSI, a SINR, or a SNR from at least oneUE. The computer-readable medium further includes code for receiving arequest to change at least one of the first number of the plurality ofantenna elements at the base station or the first transmission powerlevel at the base station. The computer-readable medium further includescode for determining, by the base station, the first number of theplurality of antenna elements based on at least one of a size of theantenna array, a coverage area for the antenna array, a codebook size, alatency, a phase calibration error, an amplitude calibration error, or afraction of failed antenna elements. The computer-readable mediumfurther includes code for determining, by the base station, the firsttransmission power level based on at least one of a size of the antennaarray, a coverage area for the antenna array, a codebook size, alatency, a phase calibration error, an amplitude calibration error, or afraction of failed antenna elements.

The computer-readable medium further includes code for determining, bythe base station, the second number of the plurality of antenna elementsbased on a comparison between the measurement report and a threshold.The computer-readable medium further includes code for determining, bythe base station, the second transmission power level based on acomparison between the measurement report and a threshold. In anexample, the first number of the plurality of antenna elements isgreater than the second number of the plurality of antenna elements, andthe first transmission power level is less than the second transmissionpower level. In another example, the first number of the plurality ofantenna elements is less than the second number of the plurality ofantenna elements, and the first transmission power level is greater thanthe second transmission power level.

The computer-readable medium further includes code for transmitting thesecond communication signal by applying a codebook including beamformingweights. The computer-readable medium further includes code foradjusting, by the base station, the beamforming weights in the codebookbased on the measurement report. The computer-readable medium furtherincludes code for transmitting the first communication signal bytransmitting the first communication signal to a UE via a transmissionpoint remote from the BS, the transmission point including the antennaarray.

Embodiments of the present disclosure further include acomputer-readable medium having program code recorded thereon, theprogram code including code for receiving, by a user equipment from abase station, a first communication signal; code for transmitting, bythe user equipment to the base station, a request to change at least oneof an antenna array size at the base station or a transmit power levelat the base station based on the first communication signal; and codefor receiving, by the user equipment from the base station, a secondcommunication signal in response to the request.

The computer-readable medium further includes code for receiving thefirst communication signal from a transmission point remote from thebase station. The computer-readable medium further includes code fortransmitting to the base station, a metric corresponding to a best beampair at the user equipment, where the second communication signal is inresponse to the metric. The metric is at least one of a RSRP, a RSRQ, aRSSI, a SINR, a SNR corresponding to the best beam pair at the UE.

In an additional aspect of the disclosure, an apparatus includes meansfor transmitting (e.g., transceiver 410 or calibration module 408) afirst communication signal using a first number of a plurality ofantenna elements and a first transmission power level; means forreceiving (e.g., transceiver 410 or report module 409), from at leastone user equipment, a measurement report based on the firstcommunication signal; and means for transmitting (e.g., transceiver 410or calibration module 408) a second communication signal using a secondnumber of the plurality of antenna elements and a second transmissionpower level based on the measurement report (e.g., feedback 230), wherethe at least one of the first number of the plurality of antennaelements is different from the second number of the plurality of antennaelements or the first transmission power level is different from thesecond transmission power level.

The apparatus further includes means for receiving (e.g., transceiver410 or report module 409) at least one of a RSRP, a RSRQ, a RSSI, aSINR, or a SNR from at least one UE. The apparatus further includesmeans for receiving (e.g., transceiver 410 or report module 409) arequest to change at least one of the first number of the plurality ofantenna elements at the base station or the first transmission powerlevel at the base station. The apparatus further includes means fordetermining (e.g., processor 402 or calibration module 408), by the basestation, the first number of the plurality of antenna elements based onat least one of a size of the antenna array, a coverage area for theantenna array, a codebook size, a latency, a phase calibration error, anamplitude calibration error, or a fraction of failed antenna elements.The apparatus further includes means for determining (e.g., processor402 or calibration module 408), by the base station, the firsttransmission power level based on at least one of a size of the antennaarray, a coverage area for the antenna array, a codebook size, alatency, a phase calibration error, an amplitude calibration error, or afraction of failed antenna elements.

The apparatus further includes means for determining (e.g., processor402 or calibration module 408), by the base station, the second numberof the plurality of antenna elements based on a comparison between themeasurement report and a threshold. The apparatus further includes meansfor determining (e.g., processor 402 or calibration module 408), by thebase station, the second transmission power level based on a comparisonbetween the measurement report and a threshold. In an example, the firstnumber of the plurality of antenna elements is greater than the secondnumber of the plurality of antenna elements, and the first transmissionpower level is less than the second transmission power level. In anotherexample, the first number of the plurality of antenna elements is lessthan the second number of the plurality of antenna elements, and thefirst transmission power level is greater than the second transmissionpower level.

The apparatus further includes means for transmitting (e.g., transceiver410 or calibration module 408) the second communication signal byapplying a codebook including beamforming weights. The apparatus furtherincludes means for adjusting (e.g., processor 402 or calibration module408), by the base station, the beamforming weights in the codebook basedon the measurement report. The apparatus further includes means fortransmitting (e.g., transceiver 410 or calibration module 408) the firstcommunication signal by transmitting the first communication signal to aUE via a transmission point remote from the BS, the transmission pointincluding the antenna array.

Embodiments of the present disclosure further include an apparatusincluding means for receiving (e.g., transceiver 510 or calibrationmodule 508), from a base station, a first communication signal; meansfor transmitting (e.g., transceiver 510 or report module 509), by theuser equipment to the base station, a request to change at least one ofan antenna array size at the base station or a transmit power level atthe base station based on the first communication signal; and means forreceiving (e.g., transceiver 510 or calibration module 508), from thebase station, a second communication signal in response to the request.

The apparatus further includes means for receiving (e.g., transceiver510 or calibration module 508) the first communication signal from atransmission point remote from the base station. The apparatus furtherincludes means for transmitting (e.g., transceiver 510 or report module509) to the base station, a metric corresponding to a best beam pair atthe user equipment, where the second communication signal is in responseto the metric. The metric is at least one of a RSRP, a RSRQ, a RSSI, aSINR, a SNR corresponding to the best beam pair at the UE.

As those of some skill in this art will by now appreciate and dependingon the particular application at hand, many modifications, substitutionsand variations can be made in and to the materials, apparatus,configurations and methods of use of the devices of the presentdisclosure without departing from the spirit and scope thereof. In lightof this, the scope of the present disclosure should not be limited tothat of the particular embodiments illustrated and described herein, asthey are merely by way of some examples thereof, but rather, should befully commensurate with that of the claims appended hereafter and theirfunctional equivalents.

What is claimed is:
 1. A method of wireless communication, comprising:transmitting, by a base station (BS) via an antenna array including aplurality of antenna elements, a first communication signal using afirst number of the plurality of antenna elements and a firsttransmission power level; receiving, by the BS from at least one userequipment (UE), one or more measurement reports based on the firstcommunication signal; and transmitting, by the BS, a secondcommunication signal using a second number of the plurality of antennaelements and a second transmission power level based on the one or moremeasurement reports, wherein at least one of the first number of theplurality of antenna elements is different from the second number of theplurality of antenna elements or the first transmission power level isdifferent from the second transmission power level.
 2. The method ofclaim 1, wherein the receiving, by the BS from at least one UE, ameasurement report includes receiving a reference signal received power(RSRP), a reference signal received quality (RSRQ), a received signalstrength indicator (RSSI), a signal-to-interference-plus-noise ratio(SINR), or a signal-to-noise ratio (SNR).
 3. The method of claim 1,wherein the receiving, by the BS from at least one UE, a measurementreport includes receiving a request to change at least one of the firstnumber of the plurality of antenna elements at the BS or the firsttransmission power level at the BS.
 4. The method of claim 1, furthercomprising: determining, by the BS, the first number of the plurality ofantenna elements based on at least one of a size of the antenna array, acoverage area for the antenna array, a codebook size, a latency, a phasecalibration error, an amplitude calibration error, or a fraction offailed antenna elements in the antenna array.
 5. The method of claim 1,further comprising: determining, by the BS, the first transmission powerlevel based on at least one of a size of the antenna array, a coveragearea for the antenna array, a codebook size, a latency, a phasecalibration error, an amplitude calibration error, or a fraction offailed antenna elements in the antenna array.
 6. The method of claim 1,further comprising: determining, by the BS, the second number of theplurality of antenna elements based on a comparison between the one ormore measurement reports and a threshold.
 7. The method of claim 1,further comprising: determining, by the BS, the second transmissionpower level based on a comparison between the one or more measurementreports and a threshold.
 8. The method of claim 1, wherein the firstnumber of the plurality of antenna elements is greater than the secondnumber of the plurality of antenna elements, and the first transmissionpower level is less than the second transmission power level.
 9. Themethod of claim 1, wherein the first number of the plurality of antennaelements is less than the second number of the plurality of antennaelements, and the first transmission power level is greater than thesecond transmission power level.
 10. The method of claim 1, whereintransmitting the second communication signal includes applying acodebook including beamforming weights.
 11. The method of claim 10,further comprising: adjusting, by the BS, the beamforming weights in thecodebook based on the measurement report.
 12. The method of claim 1,wherein transmitting the first communication signal includestransmitting the first communication signal to a UE via a transmissionpoint remote from the BS, the transmission point including the antennaarray.
 13. The method of claim 1, wherein the receiving, by the BS fromat least one UE, a measurement report includes receiving a plurality ofmeasurement reports, the method further comprising: aggregating theplurality of measurement reports; and determining, based on theaggregated measurement reports, to transmit the second communicationsignal using the second number of the plurality of antenna elements andthe second transmission power level.
 14. The method of claim 1, furthercomprising: determining to modify the number of plurality of antennaelements used for transmitting the second communication signal from thefirst number to the second number; and determining to modify thetransmission power level used for transmitting the second communicationsignal from the first transmission power level to the secondtransmission power level.
 15. An apparatus comprising: a transceiverconfigured to: transmit, by a BS via an antenna array including aplurality of antenna elements, a first communication signal using afirst number of the plurality of antenna elements and a firsttransmission power level; receive, by the BS from at least one UE, oneor more measurement reports based on the first communication signal; andtransmit, by the BS, a second communication signal using a second numberof the plurality of antenna elements and a second transmission powerlevel based on the one or more measurement reports, wherein at least oneof the first number of the plurality of antenna elements is differentfrom the second number of the plurality of antenna elements or the firsttransmission power level is different from the second transmission powerlevel.
 16. The apparatus of claim 15, wherein the measurement reportincludes at least one of a RSRP, a RSRQ, a RSSI, a SINR, a SNR from atleast one UE.
 17. The apparatus of claim 15, further comprising: aprocessor configured to determine, by the BS, at one of the first numberof the plurality of antenna elements or the first transmission powerlevel based on at least one of a size of the antenna array, a coveragearea for the antenna array, a codebook size, a latency, a phasecalibration error, an amplitude calibration error, or a fraction offailed antenna elements in the antenna array.
 18. The apparatus of claim15, further comprising: a processor configured to determine at least oneof the second number of the plurality of antenna elements or the secondtransmission power level based on a comparison between the one or moremeasurement reports and a threshold.
 19. The apparatus of claim 15,wherein the first number of the plurality of antenna elements is greaterthan the second number of the plurality of antenna elements, and thefirst transmission power level is less than the second transmissionpower level.
 20. The apparatus of claim 15, wherein the first number ofthe plurality of antenna elements is less than the second number of theplurality of antenna elements, and the first transmission power level isgreater than the second transmission power level.
 21. The apparatus ofclaim 15, further comprising: a processor configured to apply a codebookincluding beamforming weights.
 22. The apparatus of claim 21, whereinthe processor is configured to adjust the beamforming weights in thecodebook based on the measurement report.
 23. A method of wirelesscommunication, comprising: receiving, by a UE from a BS, a firstcommunication signal; transmitting, by the UE to the BS, a first requestto change an antenna array size at the BS based on the firstcommunication signal; and receiving, by the UE from the BS, a secondcommunication signal in response to the first request.
 24. The method ofclaim 23, wherein receiving the first communication signal includesreceiving the first communication signal from a transmission pointremote from the BS.
 25. The method of claim 23, further comprising:transmitting, by the UE to the BS, a metric corresponding to a best beampair at the UE, wherein the second communication signal is in responseto the metric.
 26. The method of claim 25, wherein the metric is atleast one of a RSRP, a RSRQ, a RSSI, a SINR, a SNR corresponding to thebest beam pair at the UE.
 27. The method of claim 23, furthercomprising: transmitting, by the UE to the BS, a second request tochange a transmit power level at the BS based on the first communicationsignal, wherein the receiving a second communication is in response tothe second request.
 28. The method of claim 23, further comprising:receiving, by the UE from the BS, a third communication signal;transmitting, by the UE to the BS, a second request to change a transmitpower level at the BS based on the third communication signal; andreceiving, by the UE from the BS, a fourth communication signal inresponse to the second request.
 29. An apparatus comprising: atransceiver configured to: receive, by a UE from a BS, a firstcommunication signal; transmit, by the UE to the BS, a first request tochange a transmit power level at the BS based on the first communicationsignal; and receive, by the UE from the BS, a second communicationsignal in response to the first request.
 30. The apparatus of claim 29,wherein the transceiver is configured to: receive, by the UE from theBS, a third communication signal; transmit, by the UE to the BS, a thirdrequest to change an antenna array size at the BS based on the thirdcommunication signal; and receive, by the UE from the BS, a fourthcommunication signal in response to the third request.